Different processes for degrading and converting biomass into value-adding compounds are known. Degradation of biomass in sub- or super-critical conditions is known.
WO2011/091044 discloses methods for the continuous treatment of biomass, comprising a pretreatment step, wherein said biomass is contacted with a first supercritical, near-critical, or sub-critical fluid to form a solid matrix and a first liquid fraction; and a hydrolysis step, wherein said solid matrix formed in said pretreatment step is contacted with a second super-critical or near-supercritical fluid to produce a second liquid fraction and an insoluble lignin-containing fraction. According to the processes disclosed in WO2011/091044, water, and carbon dioxide are introduced to the reactors for the degradation. Optionally acid may be added after the first pretreatment step but before a possible separation step and optionally acid may also be used in the second step, the hydrolysis reaction.
Modifications to prior art techniques are needed to improve the efficiency of converting of biomass from renewable resources and/or waste materials to more valuable products. Thus there is a need to optimize the known processes and to increase the output of degraded material.